 /*******************************************************************************
  * Copyright (c) 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.components.util;

 import java.util.Collection ;
 import java.util.Collections ;

 import org.eclipse.ui.internal.components.framework.ComponentException;
 import org.eclipse.ui.internal.components.framework.ComponentHandle;
 import org.eclipse.ui.internal.components.framework.IServiceProvider;
 import org.eclipse.ui.internal.components.framework.NonDisposingHandle;
 import org.eclipse.ui.internal.components.framework.ServiceFactory;

 /**
  * Adapts an <code>IServiceProvider</code> to an <code>AbstractServiceFactory</code>. This is
  * essentially a factory that always returns existing instances from the <code>IServiceProvider</code>.
  *
  * <p>EXPERIMENTAL: The components framework is currently under active development. All
  * aspects of this class including its existence, name, and public interface are likely
  * to change during the development of Eclipse 3.1</p>
  *
  * @since 3.1
  */
 public final class ServiceProviderToServiceFactoryAdapter extends ServiceFactory {

     private IServiceProvider target;
     
     /**
      * Creates a service factory that delegates to the given service provider.
      *
      * @param target service provider to adapt
      */
     public ServiceProviderToServiceFactoryAdapter(IServiceProvider target) {
         this.target = target;
     }
     
     /* (non-Javadoc)
      * @see org.eclipse.core.component.IContainerContext#getComponentFactory(java.lang.Object)
      */
     public ComponentHandle createHandle(Object key, IServiceProvider provider) throws ComponentException {
         Object component = target.getService(key);
         
         if (component != null) {
             return new NonDisposingHandle(component);
         }

         return null;
     }
     
     /* (non-Javadoc)
      * @see org.eclipse.core.components.IComponentContext#hasKey(java.lang.Object)
      */
     public boolean hasService(Object componentKey) {
         return target.hasService(componentKey);
     }

     /* (non-Javadoc)
      * @see org.eclipse.core.components.IComponentContext#getMissingDependencies()
      */
     public Collection getMissingDependencies() {
         // Service providers don't have dependencies
 return Collections.EMPTY_SET;
     }
     
 }

